In a search for new treatments for type 2 diabetes, researchers have discovered that implanting polymer sponges into fat tissue might offer a way forward.
So suggests new research from the University of South Carolina (USC) in Columbia that is featuring at the American Chemical Society's 254th National Meeting & Exposition, held in Washington, D.C.
The team found that 3 weeks after receiving polymer sponge implants in their fatty abdomens, obese mice with type 2 diabetes fed on a high-fat diet gained less weight and had lower levels of blood sugar than untreated equivalent mice.
Insulin is a hormone that helps cells to take up sugar from the blood so they can use it for energy. Major tissues and organs, such as the liver, brain, and skeletal muscles, need lots of blood sugar to work properly.
Body fat is an 'active organ'
Around 30.3 million people in the United States have diagnosed or undiagnosed diabetes. Approximately 95 percent of them have type 2 diabetes.
The number of U.S. adults with diabetes has more than tripled in the past 20 years, largely as a result of an aging population and rising numbers of overweight and obese people.
As yet there is no cure for diabetes, and current treatments depend heavily on patients' ability to manage them. Thus, researchers are keen to discover ways to manage diabetes that do not need patients to perform daily tasks.
Important discoveries in recent years have revealed that body fat is not just a passive reservoir of excess energy but an "active organ" that releases hormones and communicates with other parts of the body.
One member of the USC team had previously experimented with pancreatic cells embedded in polymer sponges, implanting them into the fat pads of mice with type 1 diabetes as a way to restore insulin production.
R. Michael Gower, Ph.D. - now a USC assistant professor of chemical engineering and of biomedical engineering - had done this work while at Northwestern University in Evanston, IL.
In the new study, Prof. Gower and colleagues wanted to find out what effect the polymer sponges - which are made of poly(lactide-co-glycolide) (PLG) - on their own might have on fat tissue.
The researchers regard themselves as "tissue engineers" who are addressing diabetes by restoring the communication between fat tissue and other parts of the body.
Prof. Gower explains, "When people eat poorly, don't exercise, and are under a lot of stress, they gain weight. When fat stores get too large, communication with other parts of the body breaks down and can lead to diabetes. What we're trying to do is restart that conversation."
Implanted mice improved glucose transport
The team worked with obese mice that had developed symptoms similar to those of type 2 diabetes and were fed on a high-fat diet. They implanted PLG sponges into the abdominal fat pads of the mice.
Within 1 week, the pores of the implanted PLG sponges had filled with fat cells, immune cells, and blood vessels.
After 3 weeks on the high-fat diet, the implanted mice had increased body fat by only 10 percent, whereas mice on the same diet that had not received PLG implants increased body fat by 30 percent.
When they examined the animals' calf muscles, the team found that compared with non-implanted mice, the PLG-implanted mice had 60 percent raised levels of glucose transporter type 4, which is a protein that helps to transport sugar from the blood into muscle cells.
The mice appeared to suffer no negative side effects from the polymer material, which the researchers note is present in sutures, stents, and other types of implant already in use.
The researchers are already trying to work out how the polymer sponge lessens weight gain and reduces blood sugar. After this, they will test ways to fine-tune the method and enhance its effect by encapsulating the material with bioactive compounds.
During another related study, which features at the same meeting, the team had already discovered a compound that appears to enhance the material's effects. The compound is resveratrol, which is found in red wine and other foods.
"I think what's really exciting about this work and its implications is that we're looking at how implanting this biomaterial in fat tissue, which has the ability to communicate with other organs, is affecting the whole body."
R. Michael Gower, Ph.D.